Specify the Physics Behavior

Specify the physics behavior of the air flowing through the duct.

Fluid flow physics behavior is based on various environmental effects and the application of fluid dynamics theories. For example, you can specify the impact of radiation, gravity, and heat.

In this example, you specify a particular turbulence model theory for the air flowing through the duct. If this was a duct venting air from a home appliance to the outside, you might consider gravity or thermal effects; however, here you ignore these behaviors and others. You then define a steady-state step to enable the simulation of a stable, time-insensitive flow scenario.

  1. From the Physics section of the Assistant, click Physics Behavior .
  2. From the Turbulence model options, select Realizable k-ε.

    The realizable k-ε turbulence model is appropriate for internal fluid flow scenarios like this example; other available models are suitable for external fluid flow scenarios.

  3. Click OK.
    When you define the physics behavior, the app automatically generates initial conditions with default settings. These initial conditions are located under the Scenario node in the tree.
  4. From the Physics section of the Assistant, click Steady State Step .
  5. Select Enable auto under-relaxation for all equations.

    This option gradually converges the turbulence equations to the error thresholds that you specify in the Stopping Criteria section.

  6. Expand the Stopping criteria section, and clear all of the check boxes under Residual Thresholds.

    Selecting multiple stopping criteria might result in additional iterations as the solvers attempt to satisfy all of them. In this example, you clear the residual thresholds criteria to support faster convergence.

  7. Click OK.